This invention relates to the field of devices for preventing covert opening of electronic locks, and more specifically, relates to an electronic circuit that will prevent opening the lock by the unauthorized application of power to the electronic lock.
Many safes, security containers, and/or vaults have electronic combination locks installed thereon. These locks are subject to attack in an effort to open the lock. Attacks may range from the destruction of the lock itself, an attack such that the operator can not detect that the lock has been attacked, violated, or compromised, and further to an attack such that an expert can not detect that the lock has been violated or compromised.
One particular method of attack to which electronic combination locks are particularly susceptible is an attack by an insider who has an authorized combination to the lock but who also wishes to have unauthorized access to the lock. This type of person, since they have an authorized combination, would when the lock is open, have access to the portions of the lock that are contained in the secured area when the lock is closed. Having access to this part of the lock provides the opportunity for tampering with the lock. One type of tampering to which electronic locks are particularly susceptible is wiring and/or providing an alternate power supply to the lock, which could be operated from outside the security container. Typically, this may be accomplished by providing electric power directly to the electric actuator employed in the lock, usually a motor or solenoid, which positions the bolt or which permits/conditions the lock to be opened by further operator action. Thus, it is desirable to have an electronic circuit and/or method that prevents the unauthorized opening of the lock through providing an unauthorized power source to the lock.
The present invention solves the problem discussed above and is a shorting or shunt circuit designed to allow an authorized operator to provide power to the electronic lock and which will prevent an unauthorized operator from opening the lock when an authorized combination has not been entered.